Reducing fireflies from a cycles render
Cegaton advices are good to folow to help people to help you.  

I've tried with my own textures and have the same fireflies.  

In your specific case:  


you've plug the normal in the Height slot, height is for bump map (grayscale images), with this I haven't got any fireflies at 32 samples.  
it's better to have a mesh correctlly unwrap, apply the scale before unwraping and redo the unwrap.  
too strong normal map or bump map can lead to fireflies  
not really fireflies related but when trying to recreate realistic materials, never mix a diffuse and a glossy without a fresnel effect.
Node Input--> Fresnel and plug it in the mix factor  


General advice regarding fireflies:


Personnally the most important feature when using HDRi is to set the map resolution to at least 2048, but I prefer 4096 for a good base, personnally I never go under but I'm not so limited by graphic card memory.
Go to properties tab--> world--> settings pannel--> map resolution.
An other fireflies killer and lighting killer if you don't set up corrctly, is the clamp direct in the properties tab--> sampling pannel.
To set up correctly you need to determine what is th most powerfull ray that land in your scene and adjust the value to clamp only what necessary. A bit tricky. In most case without too much risk a value between 100 to 80 make the job without altering the lighting (if you don't see light sources).  


Perhapse I'll edit my answer to give my tech if someone is interest.